respectively. In view of combinatorial geometry [1]},
the subvariety of Eq.(REF ) is changed into the subvariety of
Grassmannian \(G_{_{4,6}}\)  after taking the coincident points as a single point
in the projective space
\(&&Z_{_{4,6}}=\left(\begin{array}{cccccc}\;\;1\;\;&\;\;0\;\;&\;\;0\;\;&\;\;0\;\;&\;\;1\;\;&\;\;m_{_1}^2\;\;\\\;\;0\;\;&\;\;1\;\;&\;\;0\;\;&\;\;0\;\;&\;\;1\;\;&\;\;m_{_2}^2\;\;\\\;\;0\;\;&\;\;0\;\;&\;\;1\;\;&\;\;0\;\;&\;\;1\;\;&\;\;m_{_3}^2\;\;\\\;\;0\;\;&\;\;0\;\;&\;\;0\;\;&\;\;1\;\;&\;\;1\;\;&\;\;p^2\;\;\end{array}\right)\;.\) 
